Method of making a composite high-temperature valve

ABSTRACT

A valve head blank consisting of a briquette of water-atomized high-temperature-resistant metal powder, commonly called &#39;&#39;&#39;&#39;superalloy powder&#39;&#39;&#39;&#39; (FIGS. 1 to 5 inclusive) is compressed by the upper punch of a briquetting press in the cavity of a die containing a core rod to form a socket in the head, which is then sintered in a sintering furnace in a protective atmosphere at about 2,000* F. Meanwhile, a valve stem of ordinary steel has been cold-headed or machined at its upper end to form a slightly flared reduced-diameter nose thereon. This valve stem is placed in the die cavity of a press with its flared nose projecting upward into the die cavity. A trumpet-shaped lubricant sleeve of nonferrous metal, such as copper, is then placed in the die cavity, followed by the reheated sintered valve head with its socket telescoping with the flared nose of the valve stem. The upper punch of the press is then caused to compress and thin the valve head while at the same time to elongate and interlock the neck thereof with the flared nose of the valve stem by an extrusion action as the metal lubricant sleeve facilitates the deformation of the respective parts. Alternatively (FIGS. 6 to 9 inclusive), gas-atomized superalloy powder is molded into a valve head blank consisting of a preform in a mold also containing a core pin, this assembly being sintered in a sintering furnace as before. A flared-nose stem is again placed in the die cavity, followed by the lubricant metal sleeve and hot sintered preform, whereupon the hot-forming, extruding and elongating operation is carried out as before.

United States Patent Heller 1 51 Mar. 14, 1972 [54] METHOD OF MAKING ACOMPOSITE HIGH-TEMPERATURE VALVE [72] Inventor: John Heller, Northville,Mich.

[73] Assignee: Federal-Mogul Corporation, Southfield,

Mich.

[221 Filed: Mar. 23, 1970 [21] Appl. No.: 21,576

Related (1.8. Application Data [62] Division of Ser. No. 782,651, Dec.10, 1968, Pat. No.

[52] US. Cl. ....................29/l57.l R, 29/1567 B, 29/4205,29/4705, 29/475, 7510.5 BC, 264/12 [51] Int. Cl ..B2ld 53/00 [58]FieldofSearch ..264/l2;75/0.5 BC;25i/368; 29/1567 B, 157.1 R, 470.5,475, 420.5

[561 References Cited UNITED STATES PATENTS 881,191 3/1908 MacLachlan......................25l/368 X 1,964,687 6/1934 May ..251/368 3,124,8693/1964 Behnke ....29/l56.7 B 3,209,437 10/1965 Voorhies... ....29/l56.7B 3,244,506 4/1966 Reen ..75/0.5 BC 3,524,744 8/1970 Parikh ..75/0.5 BCX Primary Examiner-John F. Campbell Assistant Examiner-D. C. Reilly, ill

Attorney-Barthel & Bugbee [57] ABSTRACT A valve head blank consisting ofa briquette of water-atomized high-temperature-resistant metal powder,commonly called superalloy powder" (FIGS. 1 to 5 inclusive) iscompressed by the upper punch of a briquetting press in the cavity of adie containing a core rod to form a socket in the head, which is thensintered in a sinten'ng furnace in a protective atmosphere at about2,000" F. Meanwhile, a valve stem of ordinary steel has been cold-headedor machined at its upper end to form a slightly flared reduced-diameternose thereon. This valve stem is placed in the die cavity of a presswith its flared nose projecting upward into the die cavity. Atrumpet-shaped lubricant sleeve of nonferrous metal, such as copper, isthen placed in the die cavity, followed by the reheated sintered valvehead with its socket telescoping with the flared nose of the valve stem.The upper punch of the press is then caused to compress and thin thevalve head while at the same time to elongate and interlock the neckthereof with the flared nose of the valve stem by an extrusion action asthe metal lubricant sleeve facilitates the deformation of the respectiveparts.

Alternatively (FIGS. 6 to 9 inclusive), gas-atomized superalloy powderis molded into a valve head blank consisting of a preform in a mold alsocontaining a core pin, this assembly being sintered in a sinteringfurnace as before. A flared-nose stem is again placed in the die cavity,followed by the lubricant metal sleeve and hot sintered preform,whereupon the hotfon'ning, extruding and elongating operation is carriedout as before.

6 Claims, 10 Drawing Figures PATENTEDHAR 141912 R. 648 343 sum 1 [IF 2FIGI FIG. IO

lpflgmmm I 6 INVEN TO R JOHN HALLER PATENTEDMAR 14 I972 3, 648 I343 SHEI2 [IF 2 INVENTOR JOHN HALLER ATTORNEYS METHOD OF MAKING A COMPOSITEHIGH- IEMPERA'IURE VALVE This application is a division of my copendingapplication, Ser. No. 782,651 filed Dec. 10, 1968 for Composite HighTemperature Valve and Method of Making the Same, now US. Pat. No.3,583,672.

In the drawings,

FIG. I is a central vertical section through the die cavity of abriquetting press, showing the formation of a valve head briquette fromwater-atomized superalloy powder, according to the invention, with theparts shown in the positions they occupy at the end of the briquettingstroke;

FIG. 2 is a side elevation on a reduced scale of a multiplicity of valvehead briquettes upon a ceramic block ready for insertion in thesintering furnace;

FIG. 3 is a central vertical section through the die cavity of a presswith the component parts of the valve inserted in the die cavity, readyfor the start of the compression stroke;

FIG. 4 is a view similar to FIG. 3, but showing the relative positionsand proportions of the parts at the completion of the pressing stroke;

FIG. 5 is a side elevation of the trumpet-shaped nonferrous lubricantsleeve used in the pressing operation of FIGS. 3 and 4 and also of FIGS.8 and 9;

FIG. 6 is a perspective view, upon a reduced scale, of a multiple cavitymold for molding valve head preforms from gasatomized superalloy powder;

FIG. 7 is an enlarged vertical section through one of the mold cavitiesin FIG. 6, taken along the line 77 therein;

FIG. 8 is a central vertical section through the die cavity of a presswith the component parts of the valve of FIG. 7 inserted in the diecavity, ready for the start of the compression stroke;

FIG. 9 is a view similar to FIG. 8 but showing the relative positionsand proportions of the pans at the completion of the pressing stroke,and

FIG. I is a side elevation, upon a reduced scale, of the completedcomposite valve after grinding and finishing.

Referring to the drawings in detail, FIGS. 1 to inclusive illustrate theformation of a composite high-temperature-resistant valve, generallydesignated 10, shown in FIG. 10, using so-called water-atomizedsuperalloy powder, the particles of which are of irregular shape so thatthey interlock and can therefore be compacted. Superalloys are so-calledin the metal industries as being of a high chromium and cobalt content,with tungsten and nickel components in smaller proportions and withstill smaller proportions of iron, silicon, manganese and carbon. Theyare distinguished for their resistance to high-temperature deformationor surface attack and certain of these superalloys have long been knownby the name ofStellite" and by the trade designations X-40 or HS 31".The water-atomization process is well known to those skilled in this artand is not a part of the present invention. Superalloys, however, arevery expensive and ordinarily are prohibitively so for forming entirevalves. The present invention provides a composite valve 10 of which thehead I2 is of superalloy material and the stem 14 of ordinaryinexpensive steel, while the neck of the head 12 is coated with a layer18 of nonferrous lubricant metal such as copper, formed as a result ofthe process of the present invention.

The first step in the production of the head 12 of the valve 10 fromwater-atomized superalloy powder is to make a valve head blankconsisting of a briquette 20 (FIGS. 2 and 3). The briquette 20 is madein a briquetting die 22 containing a substantially cylindrical diecavity 24 which is provided with an approximately shallow conical bottomsurface 26 continuing downward in a sharply tapered conical surface 28to a reduced diameter cylindrical bore 30 coaxial with the uppercylindrical portion 32 of the die cavity 24. The die 22 is mounted in aconventional briquetting press (not shown) provided with upper and lowerpunches 34 and 36 respectively which telescope with the cylindricalportion 32 of the die cavity 24 and with the lower cylindrical bore 30of the die 22. The lower punch 36 is tubular, containing a cylindricalbore 38 in which is mounted a snugly fitted core rod 40. The core rod 40projects upward into the die cavity 24 with its top slightly below thelower end of the cylindrical portion 32 thereof. The upper punch 34 atits lower end 42 is provided with a central convex protuberance 44 forshaping the top of the briquette 20.

At the start of the formation of the briquette 20, the upper punch 34 israised completely out of the die cavity 24 while the remainder of theparts remain as shown in FIG. 1, namely the lower punch 36 and core rod40. The die cavity 24 is then filled with the water-atomized superalloypowder. The upper punch 34 is now caused to descend upon a compressionstroke, compressing the charge of superalloy powder into the shape ofthe preform 20 shown in FIG. I, under a pressure of approximately 32tons per square inch, while the protuberance 44 on the punch 34 formsthe central concavity 46 in the preform 20 and the annular peripheralportion 48 of the punch 34 forms the flat annular top portion 50 of thetop surface 60 of the briquette 20.

At the same time, the core rod 40 forms a socket $2 in the tapered neck54 of the briquette 20 below the lower conical side 56 thereof, whilethe side portion 32 of the die cavity 24 forms a side surface 58 thereonextending downward from the top surface 60. Concurrently therewith, theannular bottom surface 62 of the briquette 20 is formed by the annulartop surface 64 of the tubular lower punch 36.

When the briquetting stroke of the upper punch 34 has been completed,the upper punch 34 is retracted upward out of the die cavity 24, Thelower punch 36 is then caused to move upward upon an ejection stroke soas to eject the preform 20 from the mold cavity 24. The foregoingoperations are repeated until a suitable number of the preforms 20 hasbeen made in this manner, whereupon they are mounted upon a block 68(FIG. 2) of suitable temperature-resistant material, such as ceramic orrefractory material. The assembly is then transferred to a conventionalsintering oven where sintering is performed in a suitable protectiveatmosphere, such as dissociated ammonia, at an elevated temperature fora satisfactory period of time. In a successful practice of theinvention, a temperature pf 2,090" F. for a period of 2% hours, employedbecause of the oxide content of the water-atomized powder, whichinhibits good sintering.

Meanwhile, a valve stem 70 has been prepared from a suitable material,such as ordinary suitable carbon steel, for example that steel known inthe industry as SAE 8 l 50 steel, upon which a slightly flaredreduced-diameter nose portion 72 has been formed by cold heading or byautomatic screw machine operation. The flared nose portion 72 may becharacterized as having a reverse taper in that the upper end '74 is ofa slightly larger diameter than the lower end 76, leaving an annularmarginal shoulder '78 between the nose 72 and the shank of the valvestem 70.

The valve stem 70 is then dropped into the lower bore 82 (FIG. 3) of thedie cavity 84 of a hot-forming die 86 mounted in a conventionalhotforming press (not shown). The die cavity 84, as before, includes anupper cylindrical portion 88, an upper intermediate shallow conicalportion 90, and a lower more sharply tapered or conical surface 92opening at its lower end into the lower bore 82. The valve stem 70 is sopositioned in the lower bore 82 that the nose 72 projects upward intothe cylindrical portion 88 of the die cavity 84. A trumpetshaped orfunnel-shaped sleeve 95 approximately fivethousandths of an inch inthickness of a suitable lubricant metal (FIG. 5), such as copper, isthen dropped into the die cavity 84 over the nose portion 72 of thevalve stem 80, with its lower end coming to rest upon the annular outerupper surface 78 thereof.

The preform 20, reheated to a temperature of approximately 2,350 F. forabout 5 minutes in an endothermic atmosphere is then dropped into thedie cavity 84 within the copper sleeve 95, and with the socket 52fitting over the nose portion 72 of the stem 70 in telescopingrelationship therewith.

The upper punch 94 of the hot-forming press (FIG. 4) is then caused todescend into the die cavity 84 which it snugly but slidably fits,exerting a pressure of approximately 100 tons per square inch in asingle blow. Thereupon, the central convex protuberance 96 and theannular flat peripheral surface 98 on the lower end 100 of the punch 94form corresponding concave and flat surfaces 102 and 104 respectively onthe upper surface 106 of the top portion 108 of the now formed valvehead 110, while the side rim surface 112 acquires the configuration ofthe adjacent surface 88 of the die cavity 84. At the same time, thecompressive force exerted by the upper punch 94 densities and thins thesintered powdered metal in the prefonn 20 to form the top portion of thevalve head I10.

Meanwhile, the neck portion 54 of the briquette 20 and the nose portion72 of the valve stem 70 are extruded downward, along with the lubricantmetal sleeve 95 into the lower portion 92 of the die cavity 84,elongating these portions to form the elongated neck portion 114interlocked with the elongated nose portion 116 of the valve stem 70,and at the same time forming a layer 1 18 of nonferrous lubricant metalon the outer surface of the neck portion 114. The upper punch 94 is thenretracted upward, whereupon an ejector plunger or punch (not shown)ejects the now semifinished valve, generally designated I24]. Afterbeing allowed to cool sufficiently for handling, the semifmished valve120 is subjected to further grinding and finishing operations, togetherwith the optional formation of multiple annular grooves by conventionalturning and grinding operations, where such grooves are called for.

When several samples of the thus-formed semifinished valve were cutlongitudinally (FIG. 4), it was found that the flared neck portion 72 ofthe valve stem 70 had become stretched by the hot-forming operation soas to have become narrowed or pinched at its midportion while themidportion of the neck 54 of the briquette had bulged correspondinglytherein so as to become interlocked therewith.

The formation of the valve head blank of the compositehigh-temperature-resistant valve 10 from so-called gas atomizedsuperalloy powder (FIGS. 6 to 9 inclusive) follows a somewhat differentprocedure because of the fact that the gasatomized particles aresubstantially smooth and round, hence do not naturally interlock withone another as do the wateratomized particles, as described inconnection with FIGS. l to 5 inclusive. A graphite block mold 130 isprepared with multiple mold cavities 132 (H68. 6 and 7), each having ashape similar to that of the briquetting die cavity 24 of FIG. I. Themold I30 directly beneath the cavities 132 is provided with bottomrecesses 134 with which each mold cavity 132 communicates by way of avertical bore 136. Seated in the bore 136 is the shank I38 of a core pin140, also of graphite, and having a head 142 disposed in its recess I43and also having a slightly tapered upper end portion I44 projectingupward into the mold cavity 132.

The mold cavities 132 are filled with a charge of the gasatomiaed metalpowder compacted without the heavy briquetting compression to which thewater-atomized particles of the briquette 20 of FIGS. 1, 2 and 3 weresubjected. The thus-charged block mold 130 is then transferred to asintering furnace and sintered at a similar temperature and for asimilar period of time in a similar protective atmosphere to thatdescribed above. The mold 130 is then removed from the furnace and thepreforms l46 ejected from the mold cavities 132, leaving the preforms146 with slightly tapered sockets 148 in the neck portions 150 thereofand with head portions [52 conforming to the shapes of the mold cavities132.

A valve stem 70 is then dropped into the lower bore 82 leading to thedie cavity 84 of a hot-forming die 86 similar to that described inconnection with FIGS. 3 and 4, the same reference numerals beinghenceforth applied to corresponding parts. A trumpet-shaped lubricationsleeve 95 of nonferrous metal (FIG. 5) is then dropped into the diecavity 84 surrounding the nose portion 72 of the valve stem 70. The noseportion 72 is slightly flared, as before, A preform 146, either whilestill hot from the sintering furnace or reheated to a similartemperature, is then dropped into the die cavity 84 with its taperedsocket 148 extending downward over the nose portion 72. The upper punch94 of the hot-forming press containing the die 86 is then caused todescend into the die cavity 84 (FIG. 9), compressing and densifying thehead portion 152 and at the same time causing it to conform to the shapeof the die cavity 84 while the central convex protuberance 96 and theannular flat peripheral surface 98 on the lower end 100 of the upperpunch 94 form the corresponding concave and flat surfaces 102 and 104respectively on the upper surface 106 of the now-formed valve head "0.At the same time, the side rim surface 112 acquires the configuration ofthe adjacent surface 88 of the die cavity 84. While this is occurring,as the upper punch 94 descends it densities and thins the sinteredpowdered metal in the head portion 152 of the preform [46 to form thetop portion I08 of the valve head I10.

Simultaneously with the compression, densification and formation of thetop portion 108 of the valve head 110, the neck portion 150 of thepreform I46 and the nose portion 72 of the valve stem 70 are forceddownward, together with the lubricant metal sleeve 95 into the lowerportion 92, elongating these portions and at the same time interlockingthem, to form the elongated neck portion 114 interlocked with theelongated nose portion 116 of the valve stem 70, and at the same timeforming a thin layer 118 of nonferrous lubricant metal on the outersurface of the neck portion 114 of the valve head "0. The upper punch 94is then retracted upward, whereupon an electro plunger or punch (notshown) ejects the now semifmished valve, generally designated 120. Asbefore, the semifinished valve 120 is subsequently subjected to furthergrinding and finishing operations, together with the optional formationof multiple annular grooves 15 by conventional turning and grindingoperations where such grooves are called for.

I claim:

1. A method of making a composite high-temperature-resistant valve,comprising forming high-temperature-resistant metal alloy powder into aporous powdered metal valve head blank with an enlarged head portion anda reduced-diameter neck portion containing a socket,

sintering said blank to effect coalescence of the particles of saidmetal alloy powder,

reheating said blank,

forming from carbon steel a valve stem with a reduceddiameter noseportion thereon,

placing said valve stem and said reheated valve head blank into ahot-forming die cavity conforming to the desired final shape for saidcomposite valve with said nose portion disposed in telescopingrelationship with said socket, and

applying compressive deforming force to said valve head blank to effectcontraction of the enlarged portion thereof while effecting interlockingmating engagement of said neck portion with said nose portion.

2. A method, according to claim I, including forming said nose portionwith a flared configuration and also including constricting said neckportion into tight engagement with said flared nose portion.

3. A method, according to claim 1, including the step of placing anapproximately funnel-shaped sleeve of nonferrous lubricant metal betweensaid valve head blank and the lateral surface of said die cavity priorto applying said compressive deforming force.

4. A method, according to claim 1, wherein said metal alloy powder is awater-atomized powder, and therein said forming of said valve head blankincludes briquetting said powder in a briquetting die cavity andthereafter ejecting said valve head blank from said briquetting diecavity.

5. A method, according to claim I, wherein said metal alloy powder is agas-atomized powder, and wherein said forming of said valve head blankincludes compacting said powder in a mold cavity having a configurationcorresponding to the shape desired for said blank while forming saidsocket by means of a core member projecting into said mold cavity, andejecting said blank from said mold cavity.

6. A method, according to claim I, including the step of simultaneouslyelongated said neck portion and said nose portion while effectinginterlocking mating engagement thereof. 5

1. A method of making a composite high-temperature-resistant valve,comprising forming high-temperature-resistant metal alloy powder into aporous powdered metal valve head blank with an enlarged head portion anda reduced-diameter neck portion containing a socket, sintering saidblank to effect coalescence of the particles of said metal alloy powder,reheating said blank, forming from carbon steel a valve stem with areduced-diameter nose portion thereon, placing said valve stem and saidreheated valve head blank into a hot-forming die cavity conforming tothe desired final shape for said composite valve with said nose portiondisposed in telescoping relationship with said socket, and applyingcompressive deforming force to said valve head blank to effectcontraction of the enlarged portion thereof while effecting interlockingmating engagement of said neck portion with said nose portion.
 2. Amethod, according to claim 1, including forming said nose portion with aflared configuration and also including constricting said neck portioninto tight engagement with said flared nose portion.
 3. A method,according to claim 1, including the step of placing an approximatelyfunnel-shaped sleeve of nonferrous lubricant metal between said valvehead blank and the lateral surface of said die cavity prior to applyingsaid compressive deforming force.
 4. A method, according to claim 1,wherein said metal alloy powder is a water-atomized powder, and thereinsaid forming of said valve head blank includes briquetting said powderin a briquetting die cavity and thereafter ejecting said valve headblank from said briquetting die cavity.
 5. A method, according to claim1, wherein said metal alloy powder is a gas-atomized powder, and whereinsaid forming of said valve head blank includes compacting said powder ina mold cavity having a configuration corresponding to the shape desiredfor said blank while forming said socket by means of a core memberprojecting into said mold cavity, and ejecting said blank from said moldcavity.
 6. A method, according to claim 1, including the step ofsimultaneously elongated said neck portion and said nose portion whileeffecting interlocking mating engagement thereof.